News and New Products

UWB may yet serve whole-house video

With yet another MIMO flavor, newcomer Tzero claims to support 100-Mbps data rates to a range of 30m.

By Maury Wright, Editor in Chief -- EDN, 6/21/2006

You aren't alone if you think it's taken forever for UWB (ultrawideband) technology to hit the market. We at EDN feel like we've covered the technology and the standards battle between the WiMedia Alliance and the UWB Forum to excess. But it finally looks like real products will roll out by year's end. Moreover, newcomer Tzero Technologies is boldly claiming that its UltraMIMO technology is capable of distributing HDTV video around the typical home—the long-held goal of chip and equipment vendors in the UWB, 802.11, HomePlug, and other home-networking camps.

When UWB came on the scene early this decade, it did so with the promise of whole-home video distribution. But the FCC has severely limited the power profile of UWB networks, and most recently proponents have been focusing on networks within a single room. In fact, the most prevalent emerging usage model for UWB is as a wireless replacement for USB.

Tzero, however, isn't chasing that Wireless USB market. Instead, the company plans to market its TZ7110/TZ7210 chip set (click here for a block diagram) directly to major consumer-electronics makers. And unlike some others in the WiMedia camp, Tzero clearly believes the chips will handle video transfers beyond the living room.

The company claims to achieve a link reliability of 99%, exceeding the 95% to 98% reliability demanded by consumer-electronics vendors and the 90% reliability recommended by the WiMedia Alliance. Moreover, the company claims it can deliver that level of reliability and 100-Mbps data rates to a range of 30m with no line-of-sight requirement. Indeed, the company is demonstrating such performance through walls with no apparent buffering or other tricks.

The secret, presumably, is the compamy's UltraMIMO technology. Borrowing the "MIMO" buzzword from the 802.11 world, Tzero is also following the lead of 802.11 vendors who have stretched the term's meaning to suit their purposes. Airgo Networks was first to market with an 802.11 MIMO (multiple in, multiple out) product. That product, along with others since introduced by Airgo and others, employs spatial multiplexing, in which multiple signal channels and antennas linearly increase the bandwidth of the air channel. Other companies have used "MIMO" to refer to any wireless implementation with multiple antennas and also to beam-forming systems. Tzero's UWB implementation uses multiple antennas but only a single signal channel.

The subtle difference comes in how Tzero uses the two antennas. In most multiple-antenna wireless systems, the sender and receiver simply choose the antenna that offers the best signal strength at any given point. Tzero's chips combine the signals from the diverse antennas, and the company claims that this approach yields the signal-to-noise advantage that will enable whole-home wireless HDTV.

Tzero founder Rajeev Krishnamoorthy spends more time comparing UltraMIMO to 802.11 products than to other UWB products. In a demo, Tzero duplicated a set of tests done by PC World in "First Draft-N Routers Don't Impress," adding the Tzero design into the mix to demonstrate its superior data rate and range. The Tzero chip set will come in between the $10 going rate for 802.11g chips in high volume and the mid-$20 level expected of 802.11n chips, Krishnamoorthy claims.

We'll have to wait to see whether Tzero's story holds up outside of the company's own controlled demo. Because Tzero is focusing on the video application, it's unlikely that products using the chip set will ship until after other UWB chips become widely available.

Speaking of which, WiQuest, Wisair, and Alereon all claim to be ready to support UWB customer shipments now. Alereon has been extremely active in promoting the carriage of Bluetooth protocols over the WiMedia link. Wisair, meanwhile, just introduced a second generation of its Wireless USB hub reference design, which uses the production spin of the company's chip set. In fact, Wisair has demonstrated HDTV streams through its chip set—but not in a whole-house scenario. Serdar Yurdakul, the company's director of marketing, pledges that end products will ship with Wisair chips this year.

Finally, WiQuest is still promoting its WQST110/101 chipset, announced at the end of 2005, which doubles the prescribed WiMedia data rate to nearly 1 Gbps (see "UWB chip-set maker preps rollout of consumer products"). Neither Wisair's Yurdakul nor Tzero's Krishnamoorthy believes that faster rate offers an advantage. The 480-Mbps WiMedia rate is plenty fast for any application, including compressed HDTV video, they argue.

However, an increase to the 3-Gbps range could provide a real advantage by supporting uncompressed digital video, according to Yurdakul and Krishnamoorthy. With a link of that speed, technologies such as JPEG2000 could be used for real-time compression and transfer of uncompressed signals over UWB. Moreover, such a JPEG2000 link could maintain DRM content protection. Perhaps Analog Devices may yet find a market for the fractal-based JPEG2000 chips that it developed so long ago.